The present invention relates to turbines and pertains particularly to variable-area turbine nozzles.
Turbochargers for improving the performance of internal combustion engines are well known. One difficulty with such turbocharged engines, however, is that the engines normally are required to perform at different speeds and the turbocharger is often most effective at a specified constant speed. The turbocharger, therefore, does not normally operate efficiently at the various speeds of the engine.
One approach to the problem of providing more precise control of a turbine has been to provide variable-area nozzles at the inlet of the turbine wheel. These variable nozzles normally employ variable vanes to vary the inlet area of the nozzle to thereby control the gases to the turbine wheel.
Various mechanisms have been provided for control of variable nozzles. However, many of these present difficulties in operation. Many of the prior art devices employ cams and levers which sometimes prevent precise and proper control as well as positive control of the nozzle. Gearing has also been employed for such control; however, the gearing arrangements provided are often inefficient and lack positive and precise control.
The prior art is exemplified by the following U.S. Pat. Nos.: 3,025,036 issued Mar. 13, 1962; 2,029,067 issued Apr. 10, 1962; 3,243,159 issued Mar. 29, 1966; and 3,816,021 issued June 11, 1974.
These prior art systems have failed to provide control means for a turbocharger for making the turbocharger output correspond with engine demands.